He might have had a relationship with Sally Hemings, who was half-sister to his wife. She was actually sent to France to accompany his daughter apparently (just looked this up), which is when they speculate Jefferson began a relationship with her. The rumors were started by a political opponent. Many people claim it's a fact, and it's including black people, so he's a rapist and that's that. Other historians say it isn't proven, and that Thomas's brother or nephew was a more likely candidate, based on accounts of both their characters. So, who knows. I think he should have just freed all his slaves since he wanted it to happen anyway, but I guess it gives everyone a good reason to dunk on a Founding Father.